“A way of firing up the body's immune system in order to attack cancer has been discovered by US researchers,” reports BBC News. The immune system (if working correctly) is programmed not to attack the body’s own cells…

“A way of firing up the body's immune system in order to attack cancer has been discovered by US researchers,” reports BBC News.

The immune system (if working correctly) is programmed not to attack the body’s own cells. As cancer arises from the body’s own cells the immune system may not be able to recognise it as a threat, and therefore not attack it as vigorously as it would otherwise. Researchers are working on developing methods to get the immune system to attack the tumours but not the body’s healthy cells. This type of approach to treatment is called immunotherapy.

The current report is based on early stage research in mice, which has suggested that blocking the function of a type of immune system cell called Foxp3+ Treg cells in mice helps reduce tumour growth.

Researchers hope they will be able to use this approach to develop new treatments for human cancers. Before any human testing, there are likely to be more animal studies to ensure this approach is sufficiently safe for testing in humans.

Where did the story come from?

The study was carried out by researchers from the University of Pennsylvania and other research centres in the US. It was funded by the US National Institutes of Health.

What kind of research was this?

This was an animal study looking at whether blocking the function of one type of immune system cell, called regulatory T (Treg) cells, would help the immune system fight off cancer. Treg cells usually stop the immune system attacking the body’s own cells, but they also limit the body’s response to cancer cells. The researchers wanted to see if by reducing the effect of the Treg cells the immune system would be better at fighting off cancer.

This type of biological research is carried out in the lab and in animals as the techniques used (such as genetic engineering) would not be possible (or ethical) in humans.

Once researchers understand whether the approach works, they then need to work out a way to develop potential new treatments for human diseases. Any new treatments also need to be tested in the lab and in animals to ensure they work and are sufficiently safe to go forward to tests in humans.

This process reduces the risk of new treatments potentially causing harm, but means that developing treatments can take a long time.

What did the research involve?

The researchers used two different methods to stop a particular type of Treg cell, called Foxp3+ Treg cells, from working in mice. They then looked at what effect this had on tumour growth in these mice and whether it caused the mice’s immune systems to attack healthy cells as well.

Both methods the researchers used blocked a protein (called p300) which is needed for Treg cells to work properly. The first method used genetic engineering to delete the gene which encoded the protein from Foxp3+Treg cells. The second method used a chemical called p300i which blocks the p300 protein from working.

The effects of these methods were tested by injecting these genetically engineered or treated mice and normal mice with tumour cells under their skin and measuring tumour growth.

What were the basic results?

Mice which had been genetically engineered or treated with p300i to reduce Foxp3+ Treg cell activity showed reduced tumour growth compared with normal mice. The genetic engineering or p300i treatment did not appear to have adverse effects on other immune system cells.

How did the researchers interpret the results?

The researchers concluded that the p300 protein is important for Foxp3+ Treg cells to work properly. Blocking this protein reduced tumour growth without leading to the immune system attacking healthy cells. They say that this suggests a new approach for immunotherapy to treat cancer.

Conclusion

The current study has suggested that blocking the function of a type of immune system cell called Foxp3+ Treg cells in mice helps reduce tumour growth.

The immune system normally maintains a delicate balance in the body, fighting off infection and other external threats but not attacking the body’s own cells. This poses a problem in cancer, where the cells that pose the threat are the body’s own cells, which the immune system therefore doesn’t attack. The researchers hope that they can tip this balance enough to make the immune system attack the tumours, but not healthy cells.

While this study offers a possible new approach to doing this, more research is likely to be needed in animals to further assess the potential side effects of this treatment before this could be considered for testing in humans.